Upgrade to Sierra broke gigabit connection.

I was using gigabit ethernet under OS 10.11 now after upgrading to OS 10.12.6 I can only connect at 100Mbps. If I manually change the speed to 1000baseT and apply changes it says the cable is not connected. I have tried different settings, full & half duplex with & without flow control. I tested the ethernet cable on another mac and it works at gigabit speed.